1. Field of the Invention
The invention concerns a leak indicator for vacuum systems comprising a chamber which is evacuated while the system is in operation plus a vacuum pump used to evacuate the chamber whereby the leak indicator has a test-gas detector in the form of a mass spectrometer plus a high vacuum pump to produce the vacuum necessary for operation of the mass spectrometer.
2. Discussion of the Related Art
Before operation, after maintenance or repair work and also after other interruptions of operation, vacuum systems must be tested for the presence of leaks so as to ensure optimum operating conditions of the vacuum system which are not adversely influenced by flows of leaking gas.
From DE-OS 33 16 765 a method and device is known for the detection of leaks on turbine casings. A low pressure is maintained in the turbine casings with the aid of vacuum pumps. For the purpose of leak detection all parts of the turbine casing where a leak is suspected are sprayed from the outside with a test gas, preferably helium. The exhaust gas of the vacuum pumps is monitored with the aid of a sniffer leak indicator so that the presence of any leaks can be determined. Leak detection of this kind is relatively insensitive.
Moreover, the leak detection arrangement for this task is fairly large and heavy, because such an arrangement must include a complete high vacuum system with a heavy backing pump.